Display apparatus and driver circuit of display apparatus

• US 20050179635A1
• Filed: 02/09/2005
• Published: 08/18/2005
• Est. Priority Date: 02/10/2004
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Washio, Hajime, Murakami, Yuhichiroh
• Granted Patent: US 7,764,263 B2
• Time in Patent Office: Days
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A driver circuit of a display apparatus is provided with a nor circuit in each output line of a timing pulse. To the nor circuit, inputted are a timing pulse to be supplied to the output line and a pre-charge pulse for pre-charging a data signal line SL to which a write signal is being inputted based on the timing pulse. With this structure, it is possible to realize a driver circuit storing a pre-charge circuit of a display apparatus, which can surely prevent a collision between a pre-charge potential and a potential of a video signal in a signal supply line when pre-charging the signal supply line from a pre-charge power supply of a small driving performance, while maintaining the number of stages in the shift register to be the required minimum number

Claims

1. A driver circuit of a display apparatus, comprising:

a writing circuit having a plurality of first switches respectively provided for signal supply lines of the display apparatus, said writing circuit being provided for inputting a write signal into each of said signal supply lines by conducting each of said plurality of first switches;

a shift register having flip-flops of plural stages, said shift register being provided for sequentially outputting a timing pulse from each of said flip-flops of plural stages to conduct each of said first switches; and

a pre-charge circuit having a plurality of second switches respectively provided for the signal supply lines, said pre-charge circuit being provided for pre-charging each of said signal supply lines by conducting each of said plurality of second switches,

wherein said shift register includes a plurality of pulse signal supply circuits provided corresponding to said signal supply lines to be pre-charged while an input operation of the write signal is being carried out, and each of said pulse signal supply circuits receives a clock signal different from the timing pulse, in response to an input of the timing pulse as outputted from each of said flip-flops, and outputs as a pre-charge pulse, a pulse signal in sync with the clock signal to a second switch corresponding to a prescribed signal supply line to which the input operation of the write signal is not being carried out to conduct said second signal; and

in each output line of the timing pulse, provided is a superimposition preventing section made up of a superimposition removing circuit for removing from the timing pulse to be supplied to the output line, an overlapped part which is overlapped with the pre-charge pulse for pre-charging the signal supply line to which the input operation of the write signal is to be carried out by the timing pulse.

2. The driver circuit as set forth in claim 1, wherein:

said superimposition preventing section includes a pulse front edge cut-off circuit provided for each output line of the pre-charge pulse, said pulse front edge cut-off circuit being provided for cutting off a front edge of the pre-charge pulse to be supplied to the output line; and

the pre-charge pulse having its front edge cut off by said pulse front edge cut-off circuit is inputted to said superimposition removing circuit.

3. The driver circuit as set forth in claim 2, wherein:

said pulse front edge cut-off circuit is a delay circuit.

4. The driver circuit as set forth in claim 3, wherein said delay circuit includes:

an inverter circuit for outputting an inversed signal of the pre-charge pulse as inputted from each of said plurality of pulse signal supply circuits;

a delay inverter circuit, provided in a latter stage of said inverter circuit, which delays the inversed signal and outputs the inversed signal as delayed; and

a nor circuit, provided in a latter stage of the inverter circuit and the delay inverter circuit, which receives the inversed signal and the inversed signal as delayed by said delay inverter circuit, and outputs the pre-charge pulse based on these input signals to the superimposition removing circuit.

5. The driver circuit as set forth in claim 2, wherein:

said superimposition preventing section further includes a buffer circuit which amplifies a current of the pre-charge pulse as inputted from said pulse front edge cut-off circuit.

6. The driver circuit as set forth in claim 5, wherein:

said buffer circuit is made up of a plurality of inverter circuits of a cascade connection.

7. The driver circuit as set forth in claim 1, wherein:

each of said flip flops is a set-reset type flip flop; and

each of said plurality of pulse signal supply circuits outputs the pulse signal, also as a set signal of the flip flop in a subsequent stage of the flip flop which outputs the timing pulse.

8. The driver circuit as set forth in claim 2, wherein:

each of said flip flop is a set-reset type flip flop; and

each of said plurality of pulse signal supply circuits outputs the pulse signal, also as a set signal of the flip flop in a subsequent stage of the flip flop which outputs the timing pulse.

9. The driver circuit as set forth in claim 1, wherein:

said pulse signal supply circuit is a switch circuit.

10. The driver circuit as set forth in claim 2, wherein:

said pulse signal supply circuit is a switch circuit.

11. The driver circuit as set forth in claim 1, wherein:

said pulse signal supply circuit is a level shifter circuit.

12. The driver circuit as set forth in claim 2, wherein:

said pulse signal supply circuit is a level shifter circuit.

13. The driver circuit as set forth in claim 1, wherein:

said output lines of the timing pulse are provided in number corresponding to the number of the signal supply lines so as to sequentially conduct each of said plurality of first switches; and

said pulse signal supply circuits are provided in number corresponding to the number of the signal supply lines so as to sequentially conduct each of said plurality of second switches.

14. The driver circuit as set forth in claim 2, wherein:

said output lines of the timing pulse are provided in number corresponding to the number of the signal supply lines so as to sequentially conduct each of said plurality of first switches; and

said pulse signal supply circuits are provided in number corresponding to the number of the signal supply lines so as to sequentially conduct each of said plurality of second switches.

15. The driver circuit as set forth in claim 1, wherein:

said output lines of the timing pulse are provided in number corresponding to the number of groups of the signal supply lines, each group being made up of signal supply lines in number of i (i is an integer of not smaller than

     2), so as to conduct said plurality of first switches in such a manner that first switches in a same group conduct all at the same time, and the first switches in respective groups sequentially conduct; and

said pulse signal supply circuits are provided in number corresponding to the number of the groups of signal supply lines so as to conduct said plurality of second switches in such a manner that second switches in a same group conduct all at the same time, and the second switches in respective groups sequentially conduct.

16. The driver circuit as set forth in claim 1, wherein:

said output lines of the timing pulse are provided in number corresponding to the number of groups of the signal supply lines, each group being made up of signal supply lines in number of i (i is an integer of not smaller than

     2), so as to conduct said plurality of first switches in such a manner that first switches in a same group conduct all at the same time, and the first switches in respective groups sequentially conduct; and

said pulse signal supply circuits are provided in number corresponding to the number of the groups of signal supply lines so as to conduct said plurality of second switches in such a manner that second switches in a same group conduct all at the same time, and the second switches in respective groups sequentially conduct.

17. A display apparatus comprising:

a plurality of pixels;

a plurality of data signal lines which serve as a plurality of signal supply lines, said plurality of data signal lines being provided so as to correspond to said plurality of pixels;

a plurality of scanning signal lines which serve as a plurality of signal supply lines, said plurality of scanning signal lines being provided so as to correspond to said plurality of pixels,

a data signal line driver for writing a video signal as a write signal in said plurality of data signal lines and said plurality of pixels; and

a scanning signal line driver for writing a scanning signal as a write signal in said plurality of scanning signal lines for selecting a pixel to which the video signal is written,

wherein said data signal line driver comprises;

a writing circuit having a plurality of first switches respectively provided for signal supply lines of the display apparatus, said writing circuit being provided for inputting a write signal into each of said signal supply lines by conducting each of said plurality of first switches;

a shift register having flip-flops of plural stages, said shift register being provided for sequentially outputting a timing pulse from each of said flip-flops of plural stages to conduct each of said first switches; and

a pre-charge circuit having a plurality of second switches respectively provided for the signal supply lines, said pre-charge circuit being provided for pre-charging each of said signal supply lines by conducting each of said plurality of second switches,

wherein said shift register includes a plurality of pulse signal supply circuits provided corresponding to said signal supply lines to be pre-charged while an input operation of the write signal is being carried out, and each of said pulse signal supply circuits receives a clock signal different from the timing pulse, in response to an input of the timing pulse as outputted from each of said flip-flops, and outputs as a pre-charge pulse, a pulse signal in sync with the clock signal to a second switch corresponding to a prescribed signal supply line to which the input operation of the write signal is not being carried out to conduct said second signal; and

in each output line of the timing pulse, provided is a superimposition preventing section made up of a superimposition removing circuit for removing from the timing pulse to be supplied to the output line, an overlapped part which is overlapped with the pre-charge pulse for pre-charging the signal supply line to which the input operation of the write signal is to be carried out by the timing pulse.

18. The display apparatus as set forth in claim 17, wherein:

said superimposition preventing section of said driver circuit further includes;

a pulse front edge cut-off circuit provided for each output line of the pre-charge pulse, said pulse front edge cut-off circuit being provided for cutting off a front-edge of the pre-charge pulse to be supplied to the output line; and

the pre-charge pulse having its front edge cut-off by said pulse front edge cut-off circuit is inputted to said superimposition removing circuit.

19. The display apparatus as set forth in claim 18, wherein:

said pulse front edge cut-off circuit is a delay circuit.

20. The display apparatus as set forth in claim 19, wherein said delay circuit includes:

an inverter circuit for outputting an inversed signal of the pre-charge pulse as inputted from each of said plurality of pulse signal supply circuits;

a delay inverter circuit, provided in a latter stage of said inverter circuit, which delays the inversed signal and outputs the inversed signal as delayed; and

a nor circuit, provided in a latter stage of the inverter circuit and the delay inverter circuit, which receives the inversed signal and the inversed signal as delayed by said delay inverter circuit, and outputs the pre-charge pulse based on these input signals to the superimposition removing circuit.

21. The display apparatus as set forth in claim 18, wherein:

said superimposition preventing section of said driver circuit further includes a buffer circuit which amplifies a current of the pre-charge pulse as inputted from said pulse front edge cut-off circuit.

22. The display apparatus as set forth in claim 21, wherein:

said buffer circuit is made up of a plurality of inverter circuits of a cascade connection.

23. The display apparatus as set forth in claim 17, wherein:

each of said flip flops is a set-reset type flip flop; and

each of said plurality of pulse signal supply circuits outputs the pulse signal, also as a set signal of the flip flop in a subsequent stage of the flip flop which outputs the timing pulse.

24. The display apparatus as set forth in claim 17, wherein:

said pulse signal supply circuit of said driver circuit is a switch circuit.

25. The display apparatus as set forth in claim 17, wherein:

said pulse signal supply circuit of said driver circuit is a level shifter circuit.

26. The driver circuit as set forth in claim 17, wherein:

in said driver circuit,

said output lines of the timing pulse are provided in number corresponding to the number of the signal supply lines so as to sequentially conduct each of said plurality of first switches; and

said pulse signal supply circuits are provided in number corresponding to the number of the signal supply lines so as to sequentially conduct each of said plurality of second switches.

27. The display apparatus as set forth in claim 17, wherein:

in said driver circuit,

said output lines of the timing pulse are provided in number corresponding to the number of groups of the signal supply lines, each group being made up of signal supply lines in number of i (i is an integer of not smaller than

     2), so as to conduct said plurality of first switches in such a manner that first switches in a same group conduct all at the same time, and the first switches in respective groups sequentially conduct; and

said pulse signal supply circuits are provided in number corresponding to the number of the groups of signal supply lines so as to conduct said plurality of second switches in such a manner that second switches in a same group conduct all at the same time, and the second switches in respective groups sequentially conduct.